Part I: Questions on Chapter 1

1. Consider a packet of length L which begins at end system A and travels over three links to a destination end system. These three links are connected by two packet switches. Let d_i, s_i, and R_i denote the length, propagation speed, and the transmission rate of link i, for i = 1, 2, 3. The packet switch delays each packet by d_proc. Assuming no queuing delays, in terms of d_i, s_i, R_i, (i = 1,2,3), and L, what is the total end-to-end delay for the packet? Suppose now the packet is 1,500 bytes, the propagation speed on all three links is 2.5 * 10^8 m/s, the transmission rates of all three links are 2 Mbps, the packet switch processing delay is 3 msec, the length of the first link is 5,000 km, the length of the second link is 4,000 km, and the length of the last link is 1,000 km. For these values, what is the end-to-end delay?
   
   
2. In this problem, you will explore network delays and network paths using traceroute. Choose a destination host in North America. Perform Traceroute to that host at three different hours of the day. Choose a host such that you get response from all routers on the path. Login to any Unix machine at SFU (such as fraser.sfu.ca). Issue the Unix command  /usr/sbin/traceroute hostname.  (Alternatively, you can use tracert on Microsoft Windows in the cmd shell). Then answer the following: (a) Find the average and standard deviation of the round-trip delays at each of the three hours.  (b) Find the number of routers in the path at each of the three hours. Did the paths change during any of the hours?  (c) Try to identify the number of ISP networks that the Traceroute packets pass through from source to destination. Routers with similar names and/or similar IP addresses should be considered as part of the same ISP. In your experiments, do the largest delays occur at the peering interfaces between adjacent ISPs?

3. Suppose you would like to urgently deliver 40 terabytes data from Vancouver to Toronoto. You have available a 100 Mbps dedicated link for data transfer. Would you prefer to transmit the data via this link or instead use FedEx over-night delivery? Explain. (Note: For communication links: 1 Kbps = 1000 bps; 1 Mbps = 1000 Kbps; and so on. Whereas, for data: 1 kbits = 1024 bits; 1 Mbits = 1024 Kbits, and so on.)

Part II: Wireshark Lab

Description of this lab is given in Wireshark Lab 1.  You need to install and use the Wireshark packet sniffer/analyzer on your own computer.

Submission Instructions

• All answers must be typed in ONE file (PDF format).
• Submit electronically by the deadline at: https://courses.cs.sfu.ca/